On Thu, Oct 12, 2006 at 07:50:21PM +0200, Rob van der Heij wrote:
On 10/12/06, Ihno Krumreich [EMAIL PROTECTED] wrote:
IIRC the NTP mechanism was to review adjusting the change of the drift
every 2 seconds or so. Even though this is very little work, it does
make VM think the guest is
Rob van der Heij wrote:
There's a system TOD that is set at POR time (from the clock of the
PS/2 or so?) Unless you have the gear that will synch that from true
time, it will be off some amount.
So does this provide our cheap-as-chips solution? Run an NTP client on
the SEs and HMCs? ;-)
On 10/14/06, Vic Cross [EMAIL PROTECTED] wrote:
Rob van der Heij wrote:
There's a system TOD that is set at POR time (from the clock of the
PS/2 or so?) Unless you have the gear that will synch that from true
time, it will be off some amount.
So does this provide our cheap-as-chips
Rob,
I'm sorry if I wasn't clear enough in my example :-)
The user space doesn't typically care about the TOD - agreed. The TOD
is the TOD and the wall-clock time observed by user space may correlate
back to the TOD or may observe some +/- offset, e.g. caused by NTP.
However, the disk device
On Thu, 2006-10-12 at 00:32 +0200, Rob van der Heij wrote:
If the underlying hardware clock keeps good time, does the Linux clock
actually drift?
On zSeries, the Linux system clock was supposed to be locked to the
TOD (apart from the corrections by ntpd). That's because the TOD is
used to
On Thursday, 10/12/2006 at 12:32 ZE2, Rob van der Heij [EMAIL PROTECTED]
wrote:
Yes indeed. NTP is based on UTC which does not have time changes
:-) Technically, UTC does change due to the addition of leap seconds.
Since 1972 there have been 23 seconds added with the most recent added in
On 10/12/06, [EMAIL PROTECTED] wrote:
Yes indeed. NTP is based on UTC which does not have time changes
:-) Technically, UTC does change due to the addition of leap seconds.
Since 1972 there have been 23 seconds added with the most recent added in
December of last year. The prior change was
On Thu, Oct 12, 2006 at 12:13:13AM +0200, Rob van der Heij wrote:
On 10/11/06, Marcy Cortes [EMAIL PROTECTED] wrote:
Sure, it wastes a little, but it doesn't look that bad here (we have to
run NTP on every server to sync security tickets and stuff). Velocity
reports the idle ones at 0.01%
On 10/12/06, Ihno Krumreich [EMAIL PROTECTED] wrote:
IIRC the NTP mechanism was to review adjusting the change of the drift
every 2 seconds or so. Even though this is very little work, it does
make VM think the guest is busy and keeps it in queue. Asking the snmp
agent every minute for some
IBM announced today support for the server Time Protocol (STP) in the
zSeries hardware.
Availability of Server Time Protocol can:
* Help improve time synchronization for z9 EC, z9 BC, z990, and z890
* Support a multisite sysplex distance up to 100 km
* Synchronize servers and
-Original Message-
From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On
Behalf Of Dave Jones
Sent: Wednesday, October 11, 2006 10:01 AM
To: LINUX-390@VM.MARIST.EDU
Subject: Server Time Protocol support for zSeries
snip
Unfortunately, z/VM, and guest running under z/VM (e.g
That's a good question, John. As far as I know, Linux on zSeries (either
VM guest or native) can use an external time source to set its clock.
The real problem is that z/VM and it's guests can not use the same time
source as z/OS to sync their clocks together. Consider the case where
there are
-Original Message-
From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On
Behalf Of Dave Jones
Sent: Wednesday, October 11, 2006 10:31 AM
To: LINUX-390@VM.MARIST.EDU
Subject: Re: Server Time Protocol support for zSeries
That's a good question, John. As far as I know, Linux
, 2006 11:41 AM
To: LINUX-390@VM.MARIST.EDU
Subject: Re: Server Time Protocol support for zSeries
-Original Message-
From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On
Behalf Of Dave Jones
Sent: Wednesday, October 11, 2006 10:31 AM
To: LINUX-390@VM.MARIST.EDU
Subject: Re: Server Time
Hi John,
it is possible to use XNTP to sync the clock of the Linux boxes, but the VM
clock will not be updated, if I'm right.
On 10/11/06, McKown, John [EMAIL PROTECTED] wrote:
But why couldn't the Linux systems under z/VM use XNTP
to set their clock to the z/OS value? z/OS 1.7 can run an
-Original Message-
From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On
Behalf Of Dominic Coulombe
Sent: Wednesday, October 11, 2006 10:53 AM
To: LINUX-390@VM.MARIST.EDU
Subject: Re: Server Time Protocol support for zSeries
Hi John,
it is possible to use XNTP to sync
Port [mailto:[EMAIL PROTECTED] On Behalf Of
Richards.Bob
Sent: Wednesday, October 11, 2006 10:49 AM
To: LINUX-390@VM.MARIST.EDU
Subject: Re: Server Time Protocol support for zSeries
I'm confused as well. And it has been awhile since I played with this
(early days of sysplex timers, ETR, et al
On 10/11/06, McKown, John [EMAIL PROTECTED] wrote:
Why does Linux/zSeries need STP? I know that my home system can use XNTP
to set its clock (which I do daily). Can't XNTP be used for Linux on
zSeries just as it is for all other Linux platforms? If not, why not?
I did some work on that in the
@VM.MARIST.EDU
Subject: Re: Server Time Protocol support for zSeries
The only use case I'm aware of where standard NTP usage is not
accurate enough, but asking for ETR or STP usage is when you want
Linux to participate in an XRC asynchronous replication scheme *and*
you have a requirement for building
: Wednesday, October 11, 2006 12:05 PM
To: LINUX-390@VM.MARIST.EDU
Subject: Re: Server Time Protocol support for zSeries
The only use case I'm aware of where standard NTP usage is not
accurate enough, but asking for ETR or STP usage is when you want
Linux to participate in an XRC asynchronous
My suggestion has always been to get a 9037-2
In my understand, the STP was designed to keep a pool of z9 machines
syncronized without the need of a 9037, and it is fully supported by the
newer zOS.
One of the z9 can be syncronized with a External server (or not) and act
like the 9037 for the
-Original Message-
From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On
Behalf Of Clovis Pereira
Sent: Wednesday, October 11, 2006 12:22 PM
To: LINUX-390@VM.MARIST.EDU
Subject: Re: Server Time Protocol support for zSeries
My suggestion has always been to get a 9037-2
In my
On Wednesday, 10/11/2006 at 06:09 ZE2, Rob van der Heij
[EMAIL PROTECTED] wrote:
From what I understand of the announcement, it appears to me this is
sort of the built-in version and uses other references than a dial-up
to Boulder. If that's correct, then z/VM and Linux would still be able
to
On 10/11/06, Alan Altmark [EMAIL PROTECTED] wrote:
From what I understand of the announcement, it appears to me this is
sort of the built-in version and uses other references than a dial-up
to Boulder. If that's correct, then z/VM and Linux would still be able
to take advantage in the same
On 10/11/06, Ingo Adlung [EMAIL PROTECTED] wrote:
We are working to provide ETR support asap, but currently this
anticipated support is limited to LPAR only, as z/VM doesn't provide
the required guest support, yet. STP will follow.
No doubt the lack of my imagination, but I think it would be
Why does Linux/zSeries need STP? I know that my home system can use
XNTP
to set its clock (which I do daily). Can't XNTP be used for Linux on
zSeries just as it is for all other Linux platforms? If not, why
not?
NTP causes every guest to wake up periodically to process time updates,
which
by reply e-mail
and delete this message. Thank you for your cooperation.
-Original Message-
From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of
David Boyes
Sent: Wednesday, October 11, 2006 12:46 PM
To: LINUX-390@VM.MARIST.EDU
Subject: Re: [LINUX-390] Server Time Protocol
No doubt the lack of my imagination, but I think it would be
interesting to know which applications would take advantage of such
new function. I was not aware that people would make roll-back based
on TOD clock. All I have seen is where units of work are separated by
in-band markers and
Sure, it wastes a little, but ...
When writing The Virtualization Cookbook,
http://linuxvm.org/present/misc/virt-cookbook-2.pdf, we took Rob's
suggestion to save a few cycles by doing the following:
1) Have one zLinux server run the NTP server, xntpd, syncing to servers on
the Internet becoming
Michael MacIsaac wrote:
Sure, it wastes a little, but ...
When writing The Virtualization Cookbook,
http://linuxvm.org/present/misc/virt-cookbook-2.pdf, we took Rob's
suggestion to save a few cycles by doing the following:
1) Have one zLinux server run the NTP server, xntpd, syncing to
On 10/11/06, Marcy Cortes [EMAIL PROTECTED] wrote:
Sure, it wastes a little, but it doesn't look that bad here (we have to
run NTP on every server to sync security tickets and stuff). Velocity
reports the idle ones at 0.01% of a CPU, and that's with their agent
presumbaly doing a little stuff
On 10/11/06, John Summerfield [EMAIL PROTECTED] wrote:
If the underlying hardware clock keeps good time, does the Linux clock
actually drift?
On zSeries, the Linux system clock was supposed to be locked to the
TOD (apart from the corrections by ntpd). That's because the TOD is
used to measure
Rob van der Heij wrote:
On 10/11/06, John Summerfield [EMAIL PROTECTED] wrote:
If the underlying hardware clock keeps good time, does the Linux clock
actually drift?
On zSeries, the Linux system clock was supposed to be locked to the
TOD (apart from the corrections by ntpd). That's because
On 10/12/06, John Summerfield [EMAIL PROTECTED] wrote:
I'm feeling a little slow; is the TOD set by the operator for each VM
guest? Or managed by VM? Or, (if you have one of these features) by the
underlying hardware?
There's a system TOD that is set at POR time (from the clock of the
PS/2 or
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